Silencer

ABSTRACT

Silencer or muffler for a combustion apparatus such as an internal combustion engine or gas or oil burner, comprising two coaxial truncated cones of different widths at their wide ends, which are provided with end walls and central openings therein, the wide cone having its small end connected to the opening in the end wall of the narrow cone, and the cone angle of the two cones being in different ranges, preferably about 25* for the wide cone and preferably about 10* for the narrow cone.

United States Patent Karl Borje Olsson Hellekas, Kivik, Sweden [21] Appl. No. 90,296

[22] Filed Nov. 17, 1970 [45] Patented Sept. 28, 1971 [72] Inventor [54] SILENCER 4 Claims, 1 Drawing Fig.

[52] U.S.Cl

. 181/47B 511 rm.c| F0ln 1/02, F01nl/08,F01n7/02 [50] FieldofSearch 181/35,

[5 6] References Cited UNITED STATES PATENTS 1,611,475 12/1926 Maxim.. 1,816,245 7/1931 Wolford.

FOREIGN PATENTS 287,597 7/1931 Italy Primary Examiner-Robert S. Ward, Jr. AnorneyCushman, Darby 8:. Cushman ABSTRACT: Silencer or muffler for a combustion apparatus such as an internal combustion engine or gas or oil burner, comprising two coaxial truncated cones of different widths at their wide ends, which are provided with end walls and central openings therein, the wide cone having its small end connected to the opening in the end wall of the narrow cone, and the cone angle of the two cones being in different ranges, preferably about 25 for the wide cone and preferably about 10 for the narrow cone.

SILENCER The present invention relates to silencers or mufflers such as are used in connection with internal combustion engines or heating apparatus having a pulsating combustion.

The object of the invention is to provide a silencer which is effective in a wide range of sound wave frequencies and which is simple in construction and prevents pockets in which soot could be trapped and accumulated.

To this end, the invention relates to a silencer of the known kind comprising two truncated cones of different sizes, preferably of sheet metal, the cones being located coaxially after one another and having their wider ends facing the same direction, each cone having an end wall at its wider end provided with a central through flow opening, the smaller end of one of the cones being connected to the central opening in the end wall of the other cone. According to the invention such a silencer is characterized in that the two cones have wide ends of different width and different cone angles to form a wide cone and a narrow cone, that the wide cone has its small end connected to the central opening in the end wall of the narrow cone, and that the cone angle of the wide cone is in the range of 20 to 30", preferably about 25, whereas the cone angle of the narrow cone is in the range of 5 to 15, preferably about A great number of tests with a prototype of such a silencer according. to the invention have proved that the silencer is extremely efi'icient, particularly in relation to its simple construction.

A preferred embodiment of the invention is diagrammatically shown by way of example in the accompanying drawing, in which the silencer is shown in axial section.

The gases may flow in either direction through the silencer. Assuming that the gases enter the silencer through a pipe 10 at one end of the silencer, the gases will flow axially through the silencer and leave it through a pipe 11 or a hose. Alternatively, this pipe 1 1 may be omitted in certain applications, and in addition the pipe 10 need not extend into the silencer as shown, although this will give the best result.

The silencer comprises a wide truncated cone l2, and coaxial therewith, a narrow truncated cone 13. In the example shown, the two cones are made of sheet metal, although they can be made in other ways such as by casting.

The wide cone 12 is provided at its wider end with an end wall 14 which has a slightly conical shape that is a blunt cone angle. The pipe 10 extends through the end wall 14.

The narrow cone 13 is at its wider end provided with an end wall 15 which is slightly conical, i.e. has a blunt cone angle.

The wide cone 12 has a cone angle a which is in the range of to 30, and preferably has a value of about The narrow cone 13 has a cone angle b which is in the range of 5 to 15, and preferably has a value of about 10.

The narrow cone 13 is preferably shorter than the wide cone 12, as shown.

The smaller end of the wide cone 12 is connected to a central opening 16 in the end wall 15 of the narrow cone 13.

As shown, the diameter of the wider end of the narrow cone 13 is preferably less than half of the diameter of the wider end of the wide cone 12.

The two cones 12 and 13 are coaxial and have their wider ends facing the same direction.

To obtain the best result, the pipe 10 should extend into the interior of the wide cone l2 and have its free end 17 positioned at a distance from the end wall 14 which is about onethird of the length of the wide cone 12.

The through flow opening 16 between the two cones is of about the same size as the end opening 18 of the narrow cone 13, but has preferably a greater diameter than the inner diameter of the pipe 17.

The silencer can be connected to the combustion apparatus at its inlet or outlet end or at both ends of the apparatus. If mounted vertically with the wide cone 12 at the top, as shown, and with the gases entering through the pipe 10, it will be understood that no soot will be able to accumulate in the silencer.

In the prototype tested and shown in the drawing, the

thickness of the walls of the silencer is about 2 mm. The wide ends of the cones l2 and 13 are about and 60 mm., respectively. In operation the silencer is effective in a wide range of frequencies.

What 1 claim is:

l. Silencer for internal combustion apparatus, comprising two truncated cones of different sizes, preferably of sheet metal, the cones being located coaxially after one another and having their wider ends facing the same direction, each cone having an end wall at its wider end provided with a central through-flow opening, the smaller end of one of the cones being connected to the central opening in the end wall of the other cone, characterized in that the two cones have wide ends of different width and different cone angles to form a wide cone and a narrow cone, that the wide cone has its small end connected to the central opening in the end wall of the narrow cone, and that the cone angle of the wide cone is in the range of 20 to 30, preferably about 25, whereas the cone angle of the narrow cone is in the range of 5 to 15, preferably about l0.

2. Silencer according to claim 1, characterized in that the end walls of the two cones are conical and have a blunt cone angle facing in opposite direction relative to the small ends of the cones.

3. Silencer according to claim 1, characterized in that a central through-flow pipe extends through the end wall of the wide cone into the silencer and has its free end located at a distance from the end wall of the wide cone which is preferably about one-third of the length of the wider cone.

4. Silencer according to claim 3, characterized in that the inner diameter of the pipe through the end wall of the wider end of the wide cone is less than the diameter of the throughflow openings at both ends of the narrow cone. 

1. Silencer for internal combustion apparatus, comprising two truncated cones of different sizes, preferably of sheet metal, the cones being located coaxially after one another and having their wider ends facing the same direction, each cone having an end wall at its wider end provided with a central through-flow opening, the smaller end of one of the cones being connected to the central opening in the end wall of the other cone, characterized in that the two cones have wide ends of different width and different cone angles to form a wide cone and a narrow cone, that the wide cone has its small end connected to the central opening in the end wall of the narrow cone, and that the cone angle of the wide cone is in the range of 20* to 30*, preferably about 25*, whereas the cone angle of the narrow cone is in the range of 5* to 15*, preferably about 10*.
 2. Silencer according to claim 1, characterized in that the end walls of the two cones are conical and have a blunt cone angle facing in opposite direction relative to the small ends of the cones.
 3. Silencer according to claim 1, characterized in that a central through-flow pipe extends through the end wall of the wide cone into the silencer and has its free end located at a distance from the end wall of the wide cone which is preferably about one-third of the length of the wider cone.
 4. Silencer according to claim 3, characterized in that the inner diameter of the pipe through the end wall of the wider end of the wide cone is less than the diameter of the through-flow openings at both ends of the narrow cone. 